Such a headlight module is disclosed, for example, in WO 2010/000610 A1. This publication describes a lighting unit for vehicle headlights, said lighting unit having, as a light source, LED chips which are provided with a coating of phosphor (chip layer coating) in order to convert the blue light produced by the LED chips into white light. Said lighting unit is embodied as an integral part of a vehicle headlight and can therefore be regarded as a headlight module. In this patent application the term headlight module denotes a module which is designed for use in a headlight or is implemented as a component part of a headlight. Within the meaning of the invention, this module can be implemented as a constructional unit that is used as a single entity in a headlight, or as a system of individual, interacting components of a headlight.
The headlight module according to the invention is likewise designed primarily for use in a vehicle headlight, even though other fields of application are also possible.
In addition to the legally required low beam and high beam, high-end vehicle headlights currently also produce variable light distributions such as dynamic and static cornering light based on the provisions of ECE Regulation 123. In the near future, adaptive high beam will also be permitted. Here parts of the high-beam light are masked out in order to avoid dazzling the traffic ahead or the oncoming traffic. In addition, all current headlight systems must be designed to swivel about a horizontal axis at right angles to the direction of travel in order to provide the range adjustment of the headlight. In very high-performance headlights this adjustment must even be performed automatically as a function of the loading condition of the vehicle. Particularly in the case of the LED headlights used more recently, this means that the entire system including a heavy cooling system has to be swiveled.
For this purpose mechanical systems with stepper motors are normally used to swivel the headlight module about a horizontal axis. To implement a dynamic cornering light it is also known to swivel the headlight module about a vertical axis.
For adaptive high beam and other variable light distributions, mechanical systems with hinged shutters or rollers, by means of which the light from discharge lamps or even halogen lamps is selectively masked out, continue to be used.
Also known are so-called matrix headlights based on discharge lamps which contain an imaging element and wherein each pixel is responsible for a particular solid angle element. These headlights are referred to as pixel or matrix AFS (adaptive front lighting system) headlights. They require on the one hand a high luminance in order to keep the optical components small, and also a high luminous flux which is then—depending on the desired light distribution—largely masked out again, so that only a small part of the high luminous flux is actually used.
The advantages of an intensity modulated matrix headlight of this kind are its high resolution and therefore the possibility of dispensing with servomotors and moving components, while its disadvantage lies, on the one hand, in the high implementation costs and, on the other, in the low efficiency because of the light loss inherent in the design.
Multi-LED headlights apply light only where it is required, and can therefore in principle be more efficient. However, because of the limited number of LEDs that can be switched at acceptable cost, they do not provide enough resolution to adjust the headlight beam sufficiently finely. They therefore still require servomotors and moving parts.
To summarize, all of the currently known systems represent a compromise in terms of efficiency, cost and use of mechanical systems and therefore necessarily reliability.